DEFENCE
Software suspected
in YF-22 ATF accident
BY GRAHAM WARWICK
IN ATLANTA
The sole flyable Lockheed/ Boeing/General Dynamics
YF-22 advanced tactical fighter
(ATF) prototype crashed on the
runway at Edwards AFB, Califor
nia, on 25 April. Lockheed test
pilot Tom Morgenfeld escaped
with minor injuries, but the
aircraft was heavily damaged
and will not fly again, says the
US Air Force.
The aircraft was on a test
flight to gather data for the F-22
engineering and manufacturing
development (EMD) programme.
The crash occurred on the sec
ond of two low approaches at
Edwards. The aircraft had just
tanked for a planned supersonic
test which was cancelled because
Japan releases
OH-X requests
The Japan Technical Research and Development Institute
(TRDI) has issued a request for
proposals to Fuji, Kawasaki and
Mitsubishi for the OH-X new
scout helicopter.
The Japan Ground Self-De-
fence Force will require some
200 OH-X to operate in the
scout role for attack helicopters
from 1999. The OH-X will be
armed with a pair of lightweight
air-to-air missiles.
The OH-X, to be developed in
Japan, will be a tandem two-seat
helicopter powered by two
600kW (800shp)-class engines,
to be developed by Mitsubishi.
Composite construction will be
used extensively and the OH-X
will feature target sighting by
television and forward-looking
infra-red and laser range finding.
The companies will submit
their proposals within a month,
and the TRDI expects to select
a prime contractor in September.
OH-X development will begin in
fiscal year 1992. The total devel
opment cost is estimated at ¥78
billion ($586 million). •
of bad weather, so Morgenfeld
was burning off fuel by doing a
series of touch and goes. The
aircraft was therefore heavy,with
flaps and landing gear down.
Just before touchdown, Mor
genfeld engaged afterburner
then retracted the gear to go
around. The YF-22's thrust-
vectoring nozzles and tailerons
were observed moving rapidly
and symmetrically, and the air
craft experienced severe pitch
oscillations less than 50ft (15m)
above the runway. The pilot
appeared to shut down the en
gines to stop the pitch oscilla
tions, and make a forced
landing. The aircraft impacted the
runway gear up, skidding "several
thousand feet" and caught fire.
Morgenfeld escaped from the
aircraft on the ground. The aft
port side of the YF-22 is dam
aged where it impacted the run
way and the left side of the
aircraft is badly fire damaged.
The USAF speculates that the
combination of low altitude,
heavy aircraft, rapid cycling of
gear, flight controls and nozzles
might have put a transient maxi-
The YF-22 had met most of its flight-test objectives
mum load on the flight-control
logic. The service believes that
the software fix needed would
be relatively straightforward.
The Pratt & Whitney YF119-
powered YF-22 was one of two
prototypes built by Lockheed for
the competitive ATF demonstra
tion/validation (dem/vaf) pro
gramme. When the USAF
selected the F-22/F119 airframe/
engine combination, Lockheed
put the P&W-powered proto
type back in the air to gather
loads, vibration and acoustics
data for use in the design of the
EMD F-22.
Earlier this year the USAF
decided to curtail the planned
lOOh test programme, and flying
was scheduled to end on 27
May. The YF-22 was on its 39th
flight in the EMD phase and had
logged 61.6h when it crashed.
Including dem/val flying, the air
craft had logged 100.4h overall
in 70 flights. The USAF says the
YF-22 had accomplished more
than 90% of the test objectives.
Lockheed says the flight tests
collected all of the loads data
and most of the other high-
priority data, which is already
being used in the second F-22
internal-design iteration. The ex
ternal design has already been
frozen, and a highly accurate
windtunnel model, which will
measure aerodynamic loads, was
ready for testing in late April.
The USAF says it has no plans
for additional flight testing until
the EMD F-22's first flight in
1996. The second YF-22, which
was powered by General Electric
YF120s, is being used by Lock
heed — minus its engines — as
an engineering mockup. •
UK attack-helicopter timetable delayed
BY MIKE GAINES
The UK Ministry of Defence Procurement Executive
(MoD(PE)) says that its pre
ferred 1997 in-service date for
the Army Air Corps attack he
licopter could be delayed for up
to three years, while it waits for
the' most cost-effective replace
ment for the Westland Lynx.
The move opens the door for
Eurocopter. Its Tiger helicopter
will not be available until 1999.
The in service date is based on
12 production-standard helicop
ters, with their weapons, cleared
for service use. The current
schedule proposed by the
MoD(PE) called on manufac
turers to reply to requests for
information by 30 April. A re
quest for proposals (RFP) is
expected to be issued in Octo
ber, closing in May 1993.
The MoD(PE) expects to com
plete its review of the RFPs by
November 1993. Recommenda
tions, based on a "not-to-
exceed" price, would then be
put to the MoD Central Com
mittee for full implementation
approval in May 1994, with a
contract award expected a month
later. Fixed prices will be agreed
just before submission to the
Committee, but will need to be
made available in March 1994.
If this timetable is adhered to,
the first attack helicopter will be
delivered in March 1997. •
CASUALTIES
PAKISTAN
A Pakistan air force AAC MFI-
17B Mushak crashed on 22
April at Karachi after the solo
student bailed out. Two people
on the ground were killed.
ITALY
An Italian air force Aermacchi
MB.339 crashed into Lake
Garda on 22 April just after
take off from Villafranca AB.
The student, Lt Andrea Gas-
taldi and his instructor, Capt
Enrico Mosca, were killed.
USA
A US Air Force McDonnell
Douglas F-15C Eagle crashed
near Stuttgart, Germany, on 21
April. The pilot was killed.
2 FLIGHT INTERNATIONAL 6 - 12 May, 1992